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Prethermalization in Fermi-Pasta-Ulam-Tsingou chains
Gabriel M Lando1, Sergej Flach1
1Institute for Basic Science, Center for Theoretical Physics of Complex Systems, (IBS), Daejeon 34126, Korea.
Physical Review. E
|August 19, 2025
Summary
Short wavelength excitations in nonlinear chains amplify the Fermi-Pasta-Ulam-Tsingou (FPUT) paradox, revealing new insights into energy equipartition dynamics and prethermalization regimes.
Area of Science:
- Nonlinear dynamics
- Statistical physics
- Computational physics
Background:
- The Fermi-Pasta-Ulam-Tsingou (FPUT) paradox describes the unexpected lack of energy equipartition in nonlinear systems.
- Most research on FPUT chains focuses on long-wavelength initial states.
Purpose of the Study:
- To investigate the FPUT paradox using short-wavelength initial states.
- To develop a method for predicting mode excitation in FPUT chains.
- To explore the impact of mode excitation on energy spreading and prethermalization.
Main Methods:
- Numerical simulations of FPUT chains with short-wavelength initial states.
- Development of a predictive technique for mode excitation.
- Analysis of mode energies, spectral entropies, Lyapunov times, and Kolmogorov-Sinai entropies.
Main Results:
- Short-wavelength excitations accentuate the FPUT paradox.
- A technique was developed to predict mode excitation and perturbation order.
- Energy spreads at different speeds, leading to longer prethermalization regimes with increased mode excitation.
- Invariant quantities also exhibit prethermalization effects.
Conclusions:
- Findings generalize the FPUT experiment and offer a new perspective on the paradox's origins.
- The study enriches the understanding of equipartition in classical many-body systems.
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